1. Field of the Invention
The present invention relates generally to displaying and editing data on the Internet, and more particularly to retrieving and editing the data structure of a HTML UI (User Interface) Control.
2. Description of the Related Art
End users interact with modern computer applications through a graphical user interface (GUI). A GUI utilizes various graphical elements, such as icons, menus, forms, grids, etc. End users interact with these graphical elements using the keyboard and/or some type of pointing or selecting device, such as a mouse. By interacting with these various graphical elements, end users may carry out certain tasks or functions, such as navigation, data entry, and so on.
Of the various purposes that the GUI serves, the GUI's navigation function is vital to the usability of most applications. A properly developed navigation system empowers end users to quickly find the information they need and act upon it. One example of a commonly used navigation system is the Start menu in the Microsoft Windows operating system (OS). The Start menu allows end users to quickly find a desired application and start it. The essentialness of the navigation system is made evident by the fact that most all applications utilize it in one form or another.
Historically, one of the most effective navigation systems has been the treeview, as seen in traditional PC-based applications such as Microsoft's Windows Explorer. The treeview displays information in a hierarchical order with the broadest topic displayed at the top or the root and related items stored underneath or in nodes. Each node can have one or more child nodes, which in turn can contain additional child nodes. This hierarchical nature of the treeview works well for presenting large amounts of data that can be logically grouped. End users also prefer this type of navigation because the organized layout of the treeview helps them reach their desired information with a minimum number of steps (e.g. mouse clicks).
When it comes to managing collections of information resources, such as PC files, Web pages, and emails, the treeview is indispensable and used everyday by everyone. The most widespread and common use of a treeview is for file management (e.g. Microsoft Windows Explorer). End users manage the files on their PC's hard drive through edits performed on the displayed treeview, such as adding, deleting, and renaming interior nodes (i.e. folders) and leaves (i.e. files) of the treeview. Treeviews are also used in many other applications that involve navigating and managing collections of information resources. For example, treeviews are utilized to navigate and manage Web page bookmarks (e.g. Microsoft Internet Explorer, Netscape Navigator), emails (e.g. Microsoft Outlook, Eudora), and newsgroup articles (e.g. Microsoft Outlook Express Newsreader, Forte Free Agent).
Today's new generation of Web-based applications lack the powerful treeview of traditional PC-based applications. Early Web-based navigation systems were nothing more than various logical groupings or sets of hyperlinks presented on several Web pages. Such early navigation systems were poor at displaying a large number of hyperlinks. They either overwhelmed end users with excessive information or forced them to navigate through and download many Web pages. The much advancement in Web browser technology has enabled programmers to mimic the treeview through a Web interface; however, these treeviews are significantly less powerful than their PC-based counterparts. Generally speaking, today's treeview solutions force end users to trade functionality with speed, reliability, and security.
There are three basic groupings of treeview based on the type of technology utilized. These treeviews are grouped as Plugin-based treeviews, HTML-based treeviews, and XML-based treeviews. The shortcomings of various treeview solutions are discussed in detail below.
Plugin-based treeviews mimic the functionality of PC-based treeviews but at a hefty price. Such treeviews typically utilize either Java Applet or ActiveX technology, which are regarded as being inconvenient, slow, unreliable, and posing serious system security risks for end users. They are inconvenient because end users must generally download a Web browser plugin (depending on the type of Web browser) and periodically maintain it by downloading updates. They are slow because end users must download a relatively large amount of program code, and then wait for that code to initialize at the Web browser. They are unreliable because they are precompiled, which bypasses the Web browser's debugging feature. They pose serious system security risks because they have full read and write privileges to the end user's entire hard drive. All in all, end users must give up a lot to get the functionality of PC-based treeviews within a Web browser.
Although HTML-based treeviews overcome the pitfalls of Plugin-based treeviews, they simply lack in functionality and scalability. HTML-based treeviews are implemented using standard JavaScript and DHTML, and thus lack the server connectivity of their Plugin-based counterparts. That is, each time an interaction with the server is made, such as saving an edit made to the tree, the Web page must be refreshed. These page refreshes quickly add up as end users work, robbing them of precious time and lowering productivity. As a result, HTML-based treeviews are typically read-only so that no trips to the server are necessary. Since edits cannot be performed, such treeviews can only be used for navigating and not managing information resources. Also, the lack of server connectivity forces HTML-based treeviews to preload all its data that could be megabytes of information for larger treeviews. Consequently, HTML-based treeviews do not scale to accommodate large treeviews. These serious limitations cause HTML-based treeviews to be utilized for navigation purposes only in the context of small collections of information resources.
XML-based treeviews overcome the scalability issues of HTML-based treeviews, but still lack in functionality. XML-based treeviews add the ability to load data from an XML file to the HTML-based treeview. Though largely similar to its HTML-based counterpart, XML-based treeviews can be designed to scale to support large treeviews. This scalability comes from the fact that XML allows for read-only server connectivity. That is, XML data can be loaded into a displayed Web page at the Web browser repetitively, without incurring a page refresh. Consequently, the treeview can be engineered to incrementally load data as an end user interacts with the displayed treeview. Any editing of an XML-based treeview, however, must be done via a similar database interaction as HTML-based treeviews, which incurs a page refresh. Consequently, XML-based treeviews are typically utilized only for navigating collections of information resources.
The shortcomings of the various treeview solutions examined above are inherited from the technology utilized. As a result, other UI Controls, such as forms, grids, listviews, and menus, suffer from similar shortcomings. Specifically, the usability and scalability of other HTML UI controls is compromised, much in the same way as HTML-based treeviews, by the lack of server connectivity.
From the discussion above, it should be apparent that there is a need for an HTML-based treeview that can be used to navigate and manage large collections of information resources. More generally, it should be apparent that there is a need to improve the scalability of HTML UI Controls that display relatively large data structures, and enable HTML UI Controls to establish server connectivity as necessary without incurring a page refresh. The present invention fulfills this need.